Nuclear Reactors 52 - Jellyfish Threatening Coastal Reactors
I try to keep abreast of all the issues that involve nuclear power generation but once in a while something unexpected surprises me. I recently talked to a friend who brought up the subject of jellyfish. It seems that there has been an explosion of jellyfish in the world’s oceans. Some see this as a result of vast overfishing of the world’s ocean. Jellyfish populations rise and fall with the seasons and there are more some years than others. It has been suggested that the latest increase in jellyfish is a trend that will continue but scientists have only recently begun to track their populations.
There is some evidence that jellyfish can increase the absorption of carbon dioxide by the ocean which results in an increase of acidity. The increasing acidity interferes with the ability of a number of aquatic species to utilize the calcium dissolved in seawater. This can result in the devastation of sea life in what have come to be called “dead zones” in the world’s oceans that are devoid of most life but where jellyfish thrive. But what does this have to do with nuclear power generation?
Many nuclear reactors are located on ocean coasts and depend of seawater for reactor cooling. Some reactors have had to be shut down when the temperature of the seawater became too warm to be used for cooling. Other reactors have had problems with seaweed clogging the intakes for the cooling water. Now it appears that the threat to cooling systems on oceans coasts must include jellyfish. Nuclear power plants that draw water from the ocean for cooling have filters in the intake pipes called flumes to prevent the pipes from being clogged. Apparently these filters are not able to cope with jellyfish.
The first recent major incident occurred at the Shimane Nuclear Power Plant in Japan on June 24, 2011. The plant was attacked by hoards of jellyfish which clogged the flumes in the cooling water intake pipes. Power production dropped by six percent. A day later, the number of jellyfish near the plant fell and full power production resumed. This was the first time that jellyfish had been a problem at the plant since 1997.
The Torness Nuclear Power Station in East Lothian, Scotland had to shut down on June 30, 2011 because huge numbers of jellyfish clogged the intakes. It took days to clean the filters. The plant operators were assisted by several fishing trawlers in clearing out the jellyfish colonies near the power station.
On July 5, 2011 swarms of jellyfish threatened to shut down the Orot Rabin Nuclear Power Plant at Hadera on the coast of Israel. Plant staff worked hard to remove the jellyfish blocking the filters so that the plant could keep operating.
Swarms of jellyfish have blocked the water intakes for coastal power stations and desalinization plants occasionally during the last century. These three recent incidence could be a coincidence although the close timing is interesting. The big question is whether or not the increasing number of jellyfish in the world's oceans are going to pose an increasing threat to the operation of coastal nuclear power stations.
Jellyfish swarm:
